Our objectives are to compare cerebral organization in congenitally deaf and normal hearing subjects (Ss) using converging behavioral and electrophysiological methods. In the series of experiments proposed here we will see whether the functional specializations of the two hemispheres depends on the modality and processing demands of the language first acquired. To this end we will record evoked potentials from the two cerebral hemispheres and assess performance on lateralized tasks of language (English and American Sign Language or ASL), the perception of spatial relations (face recognition, dot localization) and tasks involving judgements of temporal order in congenitally deaf adults whose first language is ASL and in normal hearing Ss. We will also compare the cortical distribution of sensory (visual and somatosensory) evoked and motor potentials in hearing and congenitally deaf Ss to investigate the possibility that functional reorganization of cortical structures occurs with deprivation of auditory stimulation. With the results of the adult studies as a foundation, we will begin to study the relationship between the acquisition of language and the development of cerebral specialization in normal hearing children, congenitally deaf children who know ASL and in congenitally deaf children before the acquisition of speech or ASL. The results from these studies should contribute to our understanding of the normal organization of the brain and the effects of different environments on the organization of the brain.